Effect of Solution Temperature on Microstructural Evolution and Tensile Properties of Hot-rolled Haynes 230 Alloy Bar

Haynes 230 is an important candidate material for high temperature components in ultra-high temperature gas-cooled reactors， concentrating solar power and advanced ultra-supercritical coal-fired generating plants.In order to establish the alloy microstructure control criterion， it adopts the hot-rolled forming plate and adjusts the solid solution temperature，the law of microstructure evolution of the behavior of precipitation phase dissolution and the change of grain size during solution treatment were studied，The results showed that the hot-rolled plates were composed of equiaxed austenitic grains with the average grain size of 32 μm. the main precipitation phase was detected to be M₆C carbide and the metal cluster M was composed of W and Mo. The carbide content and particle size of M₆C varied little and the austenitic grains coarsened little during solution treatments in the temperature range of 950-1 150 ^oC. With the increasing of solid solution temperature to 1 180-1 200 ^oC， the carbide content of M₆C decreased， the particle size decreased， and the grain was coarening；At 1 230 ^oC and 1 250 ^oC， the dissolution of M₆C and the coarsening of grains became obviously with the average grain size to be 142 μm and 201 μm， respectively. Tensile strength at room temperature and 750 ^oC decreased slightly with the increasing solution temperature ， while tensile strength at 900 ^oC increased. The grain size and the related solution temperature was recommended to be controlled in rang of 76-142 μm and 1 200-1 230 ^oC based on the present experimental investigation， respectively.